Rotor housing of a rotary engine

ABSTRACT

A rotor housing of a rotary engine, said rotor housing being formed with bolt receiving bores extending along its wall surface in the direction of the rotor axis and closed at its opposite ends by a side housing and/or an intermediate housing clamped thereto by means of bolts passing through said bores, wherein the improvement resides in that a peripheral region of said bore is reinforced by a material which has a higher elasticity and creep limit than the material forming the body of the rotor housing.

llmted States Patent 1191 1 1 3,923,432 Nakakobara 1 1 Dec. 2, 1975 1 ROTOR HOUSING OF A ROTARY ENGINE 1791.781 2/1974 Fujiyama 418/61 A [75] Inventor: Takeshi Nakakobara, Toyota, Japan FOREIGN PATENTS Q P C TIONS [73] Assignee: Toyota Jidosha Kogyo Kabushiki 1,949,033 4/1971 Germany 418/179 Kaisha, Aichi, Japan [22] Filed: Mar. 22 1974 Primary ExaminerC. J Husar Assistant E.\aminerO. T. Sessions 1 PP N95 453,936 Attorney, Agent, or FirmStewart and Kolasch,-Ltd.

[30] Foreign Application Priority Data [57] ABSTRACT Oct. 29, 1973 Japan 1. 48-121437 A rotor housmg of a rotary engme sald rotor housmg 52 U.S. c1. 418/61 A; 418/179 bemg .fmmed 9" F F bores extend'rlg [51] Int. Cl. FOIC l/02 along Its wall Surface m the dlrectlon of the rotor axis 58 Field of Search 418/61 A, 83, 178, 179, and 9 at ends by a Side housing /or an 1ntermed1ate housmg clamped thereto by means 418/270, 123/845 1 1 of bolts passlng through saldl bores, wherem the 1m- [56] References Cited Erovernent rfesidej that atperiphegalhrigion ohf: staid ore 1s rem orce y a ma erla w 1c as a 1g er UNITED STATES PATENTS elasticity and creep limit than the material forming the 3,269,372 8/1966 Bonner 418/83 body of the rotor housing. 3,652,190 3/1972 Keller et al.. 418/179 3,715,178 2/1973 Jones .7 418/83 4 Claims, 4 Drawing Figures U.S., Patent Dec. 2, 1975 FIG. 2

FIG

CONTACT STRESS IN PORTION "A" CONTACT STRESS IN PORTION "A" (CONVENTIONAL STRUCTURE) (STRUCTURE OF THIS INVENTION) E R O B ROTOR HOUSING O-RI STRESS STRESS ROTOR HOUSING OF A ROTARY ENGINE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor housing of a rotary engine, and more particularly, an improvement of the clamping structure for the rotor housing which is clamped together with a side housing and/or an intermediate housing to define a rotor chamber therein.

2. Description of the Prior Art The rotor housing of rotary engines is generally made of an aluminium alloy, and its inside wall surface over which the tip portions of the rotor slide is provided with chromium plating or nickel-silicon carbide composite plating so that the antiwearing characteristic of the surface is improved. On the other hand, the side housing or the intermediate housing is usually made of cast iron. To assemble the rotor housing with the side and- /or intermediate housing to construct a housing for a rotary engine defining a rotor chamber therein, the rotor housing is generally formed with bolt receiving bores extending along its wall surface in the direction of the rotor axis, whereby clamping bolts are passed through said bores from one side housing positioned on one side of the rotor housing to the other side housing positioned at the opposite side of the rotor housing to clamp the rotor and side housings together. In such a conventional clamping structure, problems such as wear or exfoliation are caused due to a very small displacement between the side housing and the rotor housing. Thus, if the wear becomes serious, a clearance is formed between the clamped portions, thereby causing problems such as damage to the rubber O-rings, water leakage, etc. Such problems originate in the fact that the rotorhousing is made of an aluminium alloy because if the clamping elements are clamped together with a sufficiently high clamping torque to prevent the small displacement between the clamped portions, the rotor housing, made of an aluminium alloy, is caused to deform and loose its dimentional definitness. Thus a relatively low limit on the allowable clamping torque for the clamp bolts is necessary. Furthermore, the rotor housing made of an aluminium alloy has a relatively different coefficient of thermal expansion as compared with the side housing and the clamp bolts, such as for example, about twice as high. Therefore, although no serious problem is caused at the portion of the housing remote from the combustion chamber, where the temperature is relatively low, at that portion close to the combustion chamber where the temperature exceeds about 200C, serious problems are caused due to the fact that the clamping stress in the area where the clamping bolt is located becomes substantially higher than the average clamping stress, such that localized creeping occurs in the rotor housing made of an aluminium alloy, thereby causing a loosening between the rotor housing and the side housing.

The aforementioned problems regarding the clamping portion of the rotor and side housings are not very serious in the case of a rotary engine with the circumferential flow type cooling system wherein the clamping area is relatively large and the clamping stress is accordingly relatively low, whereas, in the case of a rotary engine with the axial flow type cooling system, the problem is frequently very serious.

SUMMARY OF THE llNVENTION Therefore, it is the object of the present invention to solve the aforementioned problems and to provide an improved clamping structure of the rotor housing whereby problems such as wear of clamping portions, the exfoliation of the plating, damage of the rubber O rings and the like which jeopardizes the normal operation of the engine caused by small displacement between the clamping portions of the rotor housing and the side and/or intermediate housings can be avoided.

According to the present invention, the aforementioned object is accomplished by a rotor housing of a rotary engine, said rotor housing being formed with bolt receiving bores extending along its wall surface in the direction of the rotor axis and closed at its opposite ends by a side housing and/or intermediate housing clamped thereto by means of bolts passed through said bores, thereby defining a rotor chamber therein, wherein a peripheral region of said bore is reinforced by a material which has a higher elasticity and creep limit than the material forming the body of the rotor housing. I 2

By reinforcing the peripheral region of the bore, through which the clamp bolt is passed, by a material having a higher elasticity than the material forming the body of the rotor housing, the compression stress acting in the rotor housing itself can be maintained at a relatively low level while also maintaining a relatively high clamping force at the contacting surfaces of the clamping portions when the clamp bolts have been clamped. Thus, the body of the rotor housing made of a relatively low compression resistant aluminium alloy is relieved from being subjected to a high compression stress. Since the reinforcing material has a higher elasticity than the material forming the body of the rotor housing, the reinforcing material reaches a higher stress condition than the material forming the body of the rotor housing even when the clamp bolts have been uniformly clamped, whereby a clamping stress necessary to keep the clamped portions in a highly stable condition is maintained. However, since the reinforcing material operates at a higher stress condition, it is of course necessary that the reinforcing material has a higher creep limit than the material forming the body of the rotor housing.

According to a particular feature of this invention, the reinforcing peripheral region of the bore may be made of a sleeve mounted in a. corresponding bore formed in the body ofthe rotor housing so that the sleeve provides a bore therein for the passage of the clamp bolt.

When a sleeve is employed to reinforce the peripheral region of the bore, opposite end faces of the sleeve should preferably be flush with end faces of the rotor housing, whereby a good and uniform contact is attained between the clamping surfaces while allowing the reinforcing sleeve to bear a larger part of the clamping stress thereby relieving the body of the rotor housing from being subject to a high stress. The material to reinforce the peripheral region of the bore may be steel or cast iron when the body of the rotor housing is made of an aluminium alloy.

BRIEF DESCRIPTION OF THE DRAWING The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention and wherein,

FIG. 1 is a longitudinal section of a housing structure wherein a. rotor housing incorporating the clamping structure accordingto the present invention is assembledwith side housings;

FIG. 2 is a section along line IIII in FIG. 1; and

FIGS. 3 and 4 are diagrams showing the contact stress conditions in Part A in FIG. 1 in the conventional structure and the structure according to the present invention for the purpose of comparison.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will be described in more detail with reference to the accompanying drawings.

Referring to FIGS. 1 and 2, reference numeral 1 designates a rotor housing which is closed at opposite ends thereof by side housings 2 thereby to define a rotor chamber 3 therein. The rotor housing and the side housings are clamped together by means of a plurality of clamp bolts 4, each of which is passed through a through bore 5 formed in the rotor housing and corresponding through bore 6 formed in the side housings. In the embodiment shown, the through bore 5 formed in the rotor housing is defined by a reinforcing sleeve 7 which forms the peripheral edge portion of the bore. 8 designates O-rings made of rubber or the like to maintained gas tightness at the clamping portions between the rotor housing and the side housings. The housing structure of a rotary engine shown in FIGS. 1 and 2 is an axial flow cooling system, and is formed with a plurality of cooling water passages 9 extending in the axial direction in the wall of the rotor housing.

When the rotor housing 1 is made of an aluminium alloy, the reinforcing sleeve 7 is preferably made of steel or cast iron.

FIGS. 3 and 4 are diagrams showing the contact stress conditions in part A for the conventional structure and the structure according to the present invention for the purpose of comparison, the latter structure incorporating the reinforcing sleeve 7. As apparent from these two Figs. in the conventional structure, a relatively high contact stress due to clamping is caused in the entire section of the rotor housing, while in the structure according to the present invention, the high contact stress due to clamping is substantially borne by the sleeve and the body portion of the rotor housing, made of an aluminium alloy, is subject only to a relatively low contact stress.

Thus, in the rotor housing incorporating the clamping structure according to the present invention, it will be understood that the rotor housing and the side housings can be firmly clamped so as not to cause wear, exfoliation of the plating, leakage, etc., due to the slight displacement between the rotor housing and the side housing without applying a high clamping contact stress to the rotor housing made of an aluminium alloy having a relatively low elasticity and creep limit.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications are intended to be included within the scope of the following claims.

I claim:

1. A rotor housing of a rotary engine, said rotor housing being formed with bolt receiving bores extending along its wall surface in the direction of the rotor axis and adapted to be closed at its opposite ends by a side housing and/or intermediate housing clamped thereto by means of bolts passing through said bores, thereby defining a rotor chamber therein wherein a sleeve is disposed in the bore to reinforce the peripheral region of said bore against compression applied in the axially direction of said bore, said sleeve being flush with the end faces of the rotor housing and being made of a material having a higher elasticity and creep limit'than that of said rotor housing.

2. The rotor housing according to claim 1, wherein said sleeve is made of steel and said rotor housing is made of an aluminum alloy.

3. The rotor housing according to claim 1, wherein said sleeve is made of cast iron and said rotor housing is made of an aluminum alloy.

4. The rotor housing according to claim 1, wherein the sleeve is contiguous with the bore and the bolt adapted to pass therethrough. 

1. A rotor housing of a rotary engine, said rotor housing being formed with bolt receiving bores extending along its wall surface in the direction of the rotor axis and adapted to be closed at its opposite ends by a side housing and/or intermediate housing clamped thereto by means of bolts passing through said bores, thereby defining a rotor chamber therein wherein a sleeve is disposed in the bore to reinforce the peripheral region of said bore against compression applied in the axially direction of said bore, said sleeve being flush with the end faces of the rotor housing and being made of a material having a higher elasticity and creep limit than that of said rotor housing.
 2. The rotor housing according to claim 1, wherein said sleeve is made of steel and said rotor housing is made of an aluminum alloy.
 3. The rotor housing according to claim 1, wherein said sleeve is made of cast iron and said rotor housing is made of an aluminum alloy.
 4. The rotor housing accordinG to claim 1, wherein the sleeve is contiguous with the bore and the bolt adapted to pass therethrough. 